Upper tool for press brake

An upper tool for a press brake in combination with an upper tool holding device mounted on an upper table of said press brake, said upper tool combination comprising:

• an clamp portion having a contact surface brought into contact with a lower surface of a support plate provided on a holder body of said upper tool holding device,
• a slide surface slidably brought into contact with a front or rear surface of said support plate,
• an inclined surface brought into pressure contact with an upper tool clamp section of an upper tool clamp member of said upper tool holding device, and
• an engage groove for engaging with an engage projection formed in said upper tool clamp member, said engage groove formed on a side surface on which said inclined surface is formed;
• and
• a work processing portion for processing a workpiece in cooperation with a lower tool, said work processing portion is provided on a lower end of said upper tool.

An upper tool assembly for a press brake, said upper tool being detachably mounted between a support plate and an upper tool clamp member, said support plate being arranged on a lower part of a holder body in an upper tool holder attached on an underside of an upper table of said press brake, said upper tool clamp member being pivotably mounted to said upper tool against said support plate, said upper tool assembly comprising:

• a contact surface which is capable of contacting with a lower end surface of said support plate, said contact surface extending perpendicularly to a longitudinal axis of a cross-section of said upper tool and formed on a first side surface of said upper tool;
• a sliding surface which is capable of sliding on a front surface or rear surface of said support plate, extending parallel to said longitudinal axis and coupled to said contact surface on said first side surface;
• an inclined surface for pivoting said upper tool clamp member to increase a clamp force of said upper tool due to said upper tool clamp member when said upper tool relatively moves with respect to said support plate so that said contact surface comes into contact with said lower end surface of said support plate, said inclined surface formed on a second side surface opposite said first side surface;
• an engage groove for engaging with an engage projection formed in said upper tool clamp member, said engage groove formed on said side surface on which said inclined surface is formed;
• and
• a processing part for cooperating with said lower tool of said press brake to process a work, said processing part provided on one end of said upper tool;
• wherein, in a condition under which a side wall of said engaging groove provided in said upper tool is supported by an engaging projection provided in said upper tool clamp member, a distance H between said lower end surface of said support plate and said contact surface of said upper tool can be calculated by a following expression:
• H=›(B.sup.2.multidot.P)!/›(A.sup.2 .multidot.k.multidot.tan .theta.)!
• wherein
• A represents a dimension of distance from a pivot center of said upper tool clamp member through an elastic means for pressing said upper tool clamp member;
• B represents a mean distance from said pivot center through a pressing point at which said upper tool clamp member presses said upper tool against said support plate;
• P represents a pressing force by which said upper tool is pressed against said support plate;
• K represents an elastic coefficient of said elastic means;
• and
• .theta. represents a slant angle of said inclined surface.

An upper tool assembly for a press brake, elastically clamped between a support plate of an upper tool holder body attached to a lower portion of an upper table and an upper tool clamp member, said upper tool comprising:

• an inclined surface narrowed toward one end of said upper tool;
• and
• an engage groove for engaging with an engage projection of said upper tool clamp member and formed adjacent said inclined surface,
• said inclined surface being brought into flush contact with a surface of said upper tool clamp member when said upper tool is clamped between said upper tool holder body support plate and said upper tool clamp member,
• wherein a clamping force on said upper tool can be increased when an other end of said upper tool is engaged with a die.